The present invention relates to a roller used in particular in continuous furnaces for heating long products, for handling and conveying iron and steel products, particularly slabs.
It is known that this type of roller must be designed and manufactured in such a way that it is suitable for:                the nature and characteristics of the products moving in the furnace, particularly as regards weight, dimensions, shape, etc.        the ambient thermal conditions in the furnace, which depend on the temperature to which the product has to be heated,        the nature of the atmosphere (oxidizing or reducing) in the furnace,        the range of speeds at which the product has to be moved in the furnace.        
These handling and conveying rollers must also be designed and manufactured in such a way that they guide the products correctly throughout the furnace while limiting the thermal marking of the products.
Additionally, the life of the rollers during which they retain their initial performance level must be sufficiently long compared with the other mechanical components of the furnace.
EP 0,345,147 describes a roller consisting of a cooled central shaft having a plurality of discs perpendicular to the geometric axis of the said shaft, each of these discs being provided with a tread in contact with the product being moved in the furnace, the discs being separated by insulating sleeves.
This technique, like all those used at the present time, is not entirely satisfactory, particularly because of the excessively limited life of the roller, due to the deterioration of the insulating sleeves caused by the mechanical stresses imparted by the deflection movements of the central shaft during the passage of the products. Thermal stresses also contribute to the deterioration of the insulating sleeves.